1. Field of the Invention
The present invention relates to a method of forming an insulating layer and a method of manufacturing a semiconductor device using the insulating layer. More particularly, the present invention relates to a method of forming an insulating layer between conductors for insulating the conductors from each other and a method of manufacturing a semiconductor device by using the insulating layer.
2. Description of the Related Art
In general, when a material having a relatively high dielectric constant is formed between conductive structures to electrically insulate the conductive structures from each other, a parasitic capacitance is generated. To help prevent a parasitic capacitance from being generated, an insulating layer including a material having a relatively low dielectric constant may be formed between the conductive structures and on the conductive structures to electrically insulate the conductive structures from each other. Particularly, the insulating layer includes an upper portion and a lower portion. The upper portion covers the upper faces of the conductive structures, and the lower portion is located below the upper portion.
The material having the relatively low dielectric constant may be hydrogen silsesquioxane (HSQ), methyl silsesquioxane (MSQ), or methyl hydrogen silsesquioxane (MHSQ).
However, hydrogen silsesquioxane is easily damaged by a stripping process using an amine solution, methyl silsesquioxane is easily damaged by an ashing process using an oxygen gas, and methyl hydrogen silsesquioxane is easily damaged by the stripping process using the amine solution as well as the ashing process using oxygen (O2).
Thus, when a contact plug is formed through the upper portion of an insulating layer to be electrically connected to the upper face of a conductive structure, a bowing may be generated.
In order to reduce the bowing, methods of forming a dual insulating layer having an upper insulating film including oxide and a lower insulating film including a material having the relatively low dielectric constant are suggested. The dual insulating film may be formed by providing an upper portion of the insulating layer with an oxygen (O2) gas or an oxygen plasma. Here, the upper portion and the lower portion of the insulating layer may correspond to the upper insulating film and the lower insulating film, respectively.
In this case, when the upper insulating film is exceedingly thick, the upper insulating film may have a relatively large dielectric constant as compared to the lower insulating film. Thus, an overall dielectric constant of the dual insulating layer may increase.
In addition, when the upper insulating film is exceedingly thick, the dual insulating layer may be excessively shrunk because oxide in the upper insulating film is formed by dehydration/condensation reactions. Furthermore, as the upper insulating film gets excessively thick, the amount of byproducts and moisture that are generated in the upper insulating film while the oxide is formed may increase. This occurs because the amount of byproducts and moisture is substantially proportional to a thickness of the upper insulating film.
Additionally, because the thickness of the upper insulating film is relatively large, the large amount of the byproducts and the moisture may not be easily removed through the upper insulating film even though a thermal treatment is performed on the upper insulating film. Thus, it is desirable to control the thickness of the upper insulating film to prevent the problems associated with an excessively thick upper insulating layer.
However, because the oxygen gas and the oxygen plasma can quickly form an excessively thick upper insulating layer, it can be hard to efficiently control the thickness of the upper insulation film.